Violent tornadoes ravished the landscape in the South on Wednesday, killing 339 people across 6 states. The hardest hit areas included 19 counties in Alabama where 250 fatalities have been reported as of 7:30am EDT. Unfortunately, this will likely not be the final death toll from the massive tornado outbreak, which yielded 263 tornadoes in a single day! The "official" tornado count will likely be reduced in the coming days, since there were numerous long tracked tornadoes on Wednesday, leading to multiple sightings of the same twisters. The red circles depicted below include tornado reports valid 6am CDT Apr 27 through 6am CDT April 28, 2011.
The Southern Tornado Outbreak of April 27, 2011 will forever change the landscape across the South and particularly for 19 counties in central and northern Alabama, where the most destructive tornadoes have been reported. Of the largest and most damaging tornadoes included the twister that dropped on Tuscaloosa, Alabama shortly after 6pm EDT. Tuscaloosa is home to the "University of Alabama" with a population just over 93,000 (July, 2009). The video and image seen below were taken from Tuscaloosa, Alabama. Notice the multiple vortices swirling counter clockwise within the parent tornado!
Video Credits to Fox6 Tuscaloosa
Remnants of a Big Lots department storm in Tuscaloosa, Alabama. Image courtesy of CNN
Another twister of epic proportions swirled across Smithville, Mississippi on Wednesday afternoon and has been rated EF-5 on the Enhanced Fujita Scale. This tornado had a path length of 2.82 miles, with a maximum width of ½ mile and estimated maximum winds near 205 miles-per-hour! The twister took 14 lives in Monroe county Mississippi. The Smithville, Mississippi tornado now stands among a small list of three EF-5 tornado reports since the Fujita Scale was revised in 2007.
Before and after; a changing landscape via high resolution satellite imagery.
250m satellite imagery from April 17, 2011 Photos courtesy of: Modis Today SSEC
250m satellite imagery from April 28, 2011 Photos courtesy of: Modis Today SSEC Notice the Tornado "Scour" marks laid by the tornadoes across Alabama.
Why were the tornadoes so strong and numerous on this day?
Several meteorological factors came together to produce a record number of tornadoes across the South on April 27, 2011. An unusually strong jet stream was a significant force, with upper level winds reaching up to 150 mph. The dip in the jet can be noted on the Telvent analysis below. The strong upper level wind support combined with southeasterly winds at the surface created the necessary directional and speed shear to produce rotating thunderstorms. The southeast winds also brought in the very warm and humid air from the Gulf of Mexico. One other factor that contributed to the outbreak was the "excessively" dry air located across much of the Southern Plains due to an ongoing severe drought. The dry air at the middle levels of the atmosphere (~10,000ft) acts to suppress thunderstorm development until strong atmospheric forcing is present .With all other factors being equal this dry air makes for even more explosive and potentially destructive thunderstorms.
So just where does the Colossal Southern Tornado Outbreak stand in the record books?
The historical tornado outbreak that occurred on April 27, 2011 currently ranks 2nd in terms of the deadliest tornado day since 1950. The "Super Outbreak of April 3 1974" took 308 lives, which is known as the deadliest tornado day since records began in 1950.
| Tornado Outbreaks >250 Deaths (WikiPedia) | Region | Tornadoes | Casualties | |
| 1925 Tri-State tornado | March 18, 1925 | Middle Mississippi - Ohio Valley | 9 | 747 fatalities, 2298 injuries |
| 1936 Tupelo-Gainesville tornado outbreak | April 5–6, 1936 | Southeastern United States | - | 454 fatalities, 2498 injuries |
| 1920 Palm Sunday tornado outbreak | March 28, 1920 | Midwest - Southeast | - | 380 fatalities, 1215 injuries |
| 1932 Deep South tornado outbreak | March 21–22, 1932 | Southeastern United States | - | 330 fatalities, 2145 injuries |
| 1908 Southeast tornado outbreak | April 23–25, 1908 | Southeastern United States | - | 324 fatalities, 1,720 injuries |
| Great Natchez Tornado | May 7, 1840 | Southeastern United States | 1 | 317 fatalities, 109 injuries |
| Super Outbreak | April 3–4, 1974 | Eastern United States - Ontario | 148 | 315 fatalities |
| 1896 St. Louis-East St. Louis tornado | May 27–28, 1896 | Missouri - Illinois / Mid-Atlantic | - | 305 fatalities, 1236 injuries |
| 1965 Palm Sunday tornado outbreak | April 11–12, 1965 | Central United States | 51 | 256 fatalities |
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May 1, 2011 at 4:42 AM I have never seen a tornado in my life as we never had one here. From what ive seen on nat geo its like a monster advancing forward and running over everything that comes in its way :(.
May the souls of victims RIP :(
Dec 3, 2011 at 9:15 PM hey Mike yeah Mike yeah! Dan Lilledahl here now living in northern Georgia! Good to see you writing on the Telvent Blog. Interesting weather down here in the south. Had the remnants of Tropical Storm Lee pass through here a few months back and gave us a few weak tornadoes. April 27 (Super Tornado Outbreak) was a scary day. Really windy and warm. Weak tornado missed my then-hometown of Newnan, GA. Witnessed some of the damage in Ringgold GA - amazing how the tornado climbed up the ridges in the area.